C# Interview Questions Level-1


1. What is C#?
2. What are the types of comment in C# with examples?
3. Can multiple catch blocks be executed?
4. What is the difference between public, static and void?
5. What is an object?
6. Define Constructors?
7. What are the Arrays in C#.Net?
8. Which class acts as a base class for all arrays in C#?
9. What is Jagged Arrays?
10. What is the difference between ref & out parameters?
11. What is the use of using statement in C#?
12. What is serialization?
13. Can "this" be used within a static method?
14. What is difference between constants and read-only?
15. What is an interface class?
16. What are value types and reference types?
17. What are Custom Control and User Control?
18. What are sealed classes in C#?
19. What is method overloading?
20. What is the difference between Array and Arraylist?
21. Can a private virtual method be overridden?
22. Describe the accessibility modifier "protected internal".
23. What are the differences between System.String and System.Text.StringBuilder classes?
24. What's the difference between the System.Array.CopyTo() and System.Array.Clone() ?
25. How can we sort the elements of the array in descending order?

C# Interview Questions Level-2


26. Write down the C# syntax to catch exception?
27. What's the difference between an interface and abstract class?
28. What is the difference between Finalize() and Dispose() methods?
29. What are circular references?
30. What are generics in C#.NET?
31. What is an object pool in .NET?
32. What are Custom Exceptions?
33. What are delegates?
34. How do you inherit a class into other class in C#?
35. What is the base class in .net from which all the classes are derived from?
36. What is the difference between method overriding and method overloading?
37. What are the different ways a method can be overloaded?
38. Why can't you specify the accessibility modifier for methods inside the interface?
39. How can we set class to be inherited, but prevent the method from being over-ridden?
40. What happens if the inherited interfaces have conflicting method names?
41. What is the difference between a Struct and a Class?
42. How to use nullable types in .Net?
43. How we can create an array with non-default values?
44. What is difference between is and as operators in c#?
45. What's a multicast delegate?
46. What are indexers in C# .NET?
47. What is difference between the "throw" and "throw ex" in .NET?
48. What are C# attributes and its significance?
49. How to implement singleton design pattern in C#?
50. What is the difference between directcast and ctype?

C# Interview Questions Level-3


51. Is C# code is managed or unmanaged code?
52. What is an Object and a Class?
53. What are the fundamental OOP concepts?
54. What is Managed and Unmanaged code?
55. What is an Interface?
56. What are the different types of classes in C#?
57. Explain Code compilation in C#.
58. What are the differences between a Class and a Struct?
59. What is the difference between Virtual method and Abstract method?
60. Explain Namespaces in C#.
61. What is “using” statement in C#?
62. Explain Abstraction.
63. Explain Polymorphism?
64. How is Exception Handling implemented in C#?
65. What are C# I/O Classes? What are the commonly used I/O Classes?
66. What is StreamReader/StreamWriter class?
67. What is a Destructor in C#?
68. What is an Abstract Class?
69. What are Boxing and Unboxing?
70. What is the difference between Continue and Break Statement?
71. What is the difference between finally and finalize block?
72. What is an Array? Give the syntax for a single and multi-dimensional array?
73. What is a Jagged Array?
74. Name some properties of Array.
75. What is an Array Class?

C# Interview Questions Level-4


76. What is a String? What are the properties of a String Class?
77. What is an Escape Sequence? Name some String escape sequences in C#.
78. What are Regular expressions? Search a string using regular expressions?
79. What is Parsing? How to Parse a Date Time String?
80. What is a Delegate? Explain.
81. What are Events?
82. How to use Delegates with Events?
83. What are the different types of Delegates?
84. What do Multicast Delegates mean?
85. Explain Publishers and Subscribers in Events.
86. What are Synchronous and Asynchronous operations?
87. What is Reflection in C#?
88. What is a Generic Class?
89. Explain Get and Set Accessor properties?
90. What is a Thread? What is Multithreading?
91. Name some properties of Thread Class.
92. What are the different states of a Thread?
93. What are Async and Await?
94. What is a Deadlock?
95. Explain Lock, Monitors, and Mutex Object in Threading.
96. What is a Race Condition?
97. What is Thread Pooling?
98. What are the types of Serialization?
99. What is an XSD file?
100. What is Managed or Unmanaged Code?

C# Interview Questions Level-5


101. What is Boxing and Unboxing?
102. What is enum in C#?
103. What is the difference between “continue” and “break” statements in C#?
104. What is the difference between constant and read only in c#?
105. What is the difference between ref and out keywords?
106. Can “this” be used within a static method?
107. Define Property in C#.net?
108. What is extension method in c# and how to use them?
109. What is the difference between dispose and finalize methods in c#?
110. What is the difference between string and StringBuilder in c#?
111. What is delegates in C# and uses of delegates?
112. What is sealed class in c#?
113. What are partial classes?
114. What is IEnumerable<> in c#?
115. What is difference between late binding and early binding in c#?
116. What are the differences between IEnumerable and IQueryable?
117. What is the Constructor Chaining in C#?
118. What’s the difference between the System.Array.CopyTo() and System.Array.Clone()?
119. Can Multiple Catch Blocks executed in c#?
120. What is Singleton Design Patterns and How to implement in C#?
121. Difference between Throw Exception and Throw Clause
122. What are Indexer in C# .Net?
123. What is multicast delegate in c#?
124. Difference between Equality Operator (==) and Equals() Method in C#
125. Difference between is and as operator in C#

C# Interview Questions Level-6


126. How to use Nullable<> Types in .Net?
127. Different Ways of Method can be overloaded
128. Describe the accessibility modifiers in c#
129. What is Virtual Method in C#?
130. What are the Difference between Array and ArrayList in C#.Net?
131. What you understand by Value types and Reference types in C#.Net?
132. What is jagged array in C#.Net?
133. What is Multithreading with .NET?
134. Explain Anonymous type in C#?
135. Explain Hashtable in C#?
136. What is LINQ in C#?
137. What is File Handling in C#.Net?
138. What is Reflection in C#.Net?
139. What is Jagged Array in C#?
140. In how many ways you can pass parameters to a method?
141. Can you return multiple values from a function in C#?
142. What is the difference between ref and out parameters?
143. What is namespace in C#?
144. What is the purpose of using statement in C#?
145. What are value types in C#
146. What are reference types in C#
147. Which class acts as a base class for all the data types in .net?
148. What is boxing in C#?
149. What is unboxing in C#?
150. What are dynamic type variables in C#

C# Interview Questions Level-7


151. What is the difference between dynamic type variables and object type variables?
152. What are pointer types in C#?
153. What is the purpose of is operator in C#?
154. What is the purpose of as operator in C#?
155. What is encapsulation?
156. How encapsulation is implemented in C#?
157. What is the purpose of an access specifier in C#?
158. What is scope of a public member variable of a C# class?
159. What is scope of a private member variable of a C# class?
160. What is scope of a protected member variable of a C# class?
161. What is scope of a Internal member variable of a C# class?
162. What is scope of a Protected Internal member variable of a C# class?
163. What are nullable types in C#?
164. What is the use of Null Coalescing Operator (??) in C#?
165. Can you create a function in C# which can accept varying number of arguments?
166. Can you pass additional type of parameters after using params in function definition?
167. How to sort an array in C#?
168. How to sort an array in C# in descending order?
169. What is a structure in C#?
170. What are the differences between a class and structure
171. What is a enumeration in C#?
172. What is the default access for a class?
173. What is the default access for a class member?
174. What is inheritance?
175. Is multiple inheritance supported in C#?

C# Interview Questions Level-8


176. How to inherit a class in C#?
177. What is polymorphism?
178. What is the difference between static polymorphism and dynamic polymorphism?
179. How C# supports static polymorphism?
180. What is early binding?
181. What is function overloading?
182. How C# supports dynamic polymorphism?
183. What is a sealed class in C#?
184. How will you create sealed abstract class in C#?
185. What are virtual functions in C#?
186. Is operator overloading supported in C#?
187. What is a preprocessor directives in C#?
188. What is the use of conditional preprocessor directive in C#?
189. Which class acts as a base class for all exceptions in C#?
190. What is the reason behind the invention of C#?
191. What are the main reasons to use C# language?
192. What are constructors in C#?
193. What are the different types of constructors in C#?
194. What is static constructor?
195. What is method overloading in C#?
196. Is overriding of a function possible in the same class?
197. Explain the process of Code compilation in C#.
198. Elucidate the difference between Virtual method and Abstract method?
199. Explain what is Namespaces in C#.
200. How is Exception Handling executed in C#?

C# Interview Questions Level-9

201. What are extension methods and where are they used?
202. How to implement the Singleton design pattern in C#?
203. What is the difference between the “throw” and “throw ex” in .NET
204. What is the use of the volatile keyword?
205. What is an async method of C#?
206. Differentiate between Object pooling and Connection pooling in C#?
207. Can you serialize hashtables and Why?
208. What is?PDB file?
209. Differentiate between Managed and Unmanaged code?
210. What is array?
211. What is ArrayList?
212. What is a collection?
213. What is the lock statement in C#?
214. How to declare a property in a class?
215. What is the difference between early binding and late binding in C#?
216. Which are the access modifiers available in C#?
217. What is the difference between abstract class and interface in C#?
218. What is the difference between dispose() and finalize() methods in C#?
219. What is the difference between method overloading and method overriding in C#?
220. What is object pool in .Net?
221. What is delegate in C#?
222. What is Hashtable?
223. What is Reflection?
224. What is Garbage Collection?
225. Explain the fundamental concepts of OOP?

C# Interview Questions Level-10


226. What are the benefits of using C#?
227. Describe the basic construction of the C# program.
228. What is an Interface in C#?
229. What are the various types of classes in C#?
230. Write a C# program that outputs “All The Best”.
231. Name any three ways to pass parameters to a method in C#?
232. How is operator Overloading achieved in C#? Explain for example?
233. Differentiate between object type and dynamic type variables.
234. What is encapsulation? How is encapsulation handled in C#?
235. What are generics in C#?
236. What is the difference between “dispose of” and “finalize” variables in C#?
237. Differentiate between Array and ArrayList in C#?
238. What is an Escape Sequence?
239. How will you know what version of the framework is your application targeting?
240. Differentiate between Static class and Singleton instance?
241. Differentiate between Managed and Unmanaged code.
242. Explain the process of Code compilation in C#.
243. Elucidate the difference between Virtual method and Abstract method?
244. Explain what is Namespaces in C#.
245. How is Exception Handling executed in C#?
246. What are extension methods and where are they used?
247. How to implement the Singleton design pattern in C#?
248. What is the difference between the “throw” and “throw ex” in .NET
249. What is the use of the volatile keyword?
250. What is an async method of C#?
251. Differentiate between Object pooling and Connection pooling in C#?
252. Can you serialize hashtables and Why?
253. What is?PDB file?
254. Differentiate between Managed and Unmanaged code?